The invention relates to an integrated circuit including a unit for controlling a load of an inductive nature, which unit including a first output transistor having a first control electrode and a first main current path, a second output transistor having a second control electrode and a second main current path, a control stage for controlling the output transistors, a first supply terminal for receiving a first supply voltage, a second supply terminal for receiving a second supply voltage, and an output terminal for connecting the load, the first and the second control electrode being coupled to the control stage, the first main current path being coupled between the first supply terminal and the output terminal, and the second main current path being coupled between the output terminal and the second supply terminal.
Such an integrated circuit including a unit for controlling a load of an inductive nature can be used inter alia in a personal computer wherein the load is constituted by a motor of a disc drive.
Such an integrated circuit comprising a unit for controlling a load of an inductive nature is known inter alia from a chip which is commercially available under the type number TDA 5140 (Philips) at the time of filing of the present document. When a load of an inductive nature is connected to the output terminal of the known unit an undesired voltage transient is produced on the output terminal when a current flowing through the load is interrupted by the output transistors, which voltage transients is caused by the inductive nature. In order to preclude the undesired voltage transient the known unit includes a first diode coupled in parallel to the first main current path and a second diode coupled in parallel to the second main current path, the first diode allowing the passage of a current flowing through the load after an interruption by the second transistor, and the second diode allowing the passage of a current flowing through the load after an interruption by the first transistor. As a result of the conduction of the first diode the undesired voltage transient on the output terminal is limited to a first voltage which differs by one diode voltage from the first supply voltage and as a result of the conduction of the second diode the undesired voltage transient on the output terminal is limited to a second voltage which differs by one diode voltage from the second supply voltage.
However, a disadvantage of the known integrated circuit including a unit for controlling a load of an inductive nature is that the first or the second voltage gives rise to a parasitic effect causing the known integrated circuit to function in an undesirable manner.